It is currently known that a shoe, in order to be comfortable, must ensure correct exchange of heat and water vapor between the microclimate inside the shoe and the external microclimate.
However, such heat and water-vapor exchanges must not compromise in any case the impermeableness of the shoe to external moisture or water.
In currently commercially available shoes, heat and water-vapor exchanges are substantially entrusted either to the upper portion of the shoe (upper) or to the sole.
As regards the upper portion of the shoe, shoes which have perforated uppers and/or are provided with linings made of vapor-permeable and waterproof material are currently commercially available.
Indeed, in some models, part of the upper may be replaced with materials which are indeed waterproof and at the same time vapor-permeable.
Another category of shoes instead entrusts transpiration to the sole, by using layers of materials which are impermeable to water and are vapor-permeable, optionally associated with protective layers and with fillers.
In order to achieve optimum exchange of heat and water vapor, a vapor-permeable shoe has been conceived which is disclosed in Italian Invention Patent Application No. PD95A000190 filed on Oct. 13, 1995 and comprises the following combination of elements:
a vapor-permeable upper associated with a vapor-permeable or perforated lining;
a tread sole made of perforated elastomer;
a mid-sole which comprises at least one membrane made of vapor-permeable waterproof material which is associated with a lower protective layer made of a material resistant to hydrolysis, water-repellent and vapor-permeable or perforated;
a vapor-permeable or perforated insole;
a vapor-permeable or perforated filler layer arranged between the insole and the membrane.
In the shoe as disclosed in Italian Invention Patent Application No. PD95A000190 filed on Oct. 13, 1995, the lower part of the upper, the thread sole and the mid-sole with the membrane are perimetrically sealed in their coupling regions. Said shoe has solved the problem of the transpiration of heat and water vapor, but it still entails some marginal drawbacks mostly during manufacture. This is because it is rather difficult to insert the rather delicate waterproof membrane precisely, safely and without damage during the assembly of the mid-sole.
Moreover, during use, the membrane, especially in shoes used in particularly demanding situations, may be subjected to such stresses as to produce undesirable damage thereto.
The aim of the present invention is to provide a vapor-permeable shoe which combines the possibility of providing heat and water-vapor exchange both through the upper and through the sole, ensuring at all times an optimum internal microclimate as a function of the external climate, with improved simplicity and precision of execution during manufacture.
Within the scope of this aim, an object of the present invention is to provide a vapor-permeable shoe in which the membrane specifically assigned to the transpiration function is protected effectively even if the shoe is used in situations which are particularly demanding as to mechanical stresses, such as in the field of sports and in the field of working shoes.
Another object of the present invention is to provide a vapor-permeable shoe which is meant both for day-to-day use and for sports use.
Another object of the present invention is to provide a vapor-permeable shoe having a competitive cost with respect to conventional vapor-permeable shoes.
Another object of the present invention is to provide a vapor-permeable shoe which can be manufactured with known technologies.
This aim, these objects and others which will become apparent hereinafter are achieved by a vapor-permeable shoe comprising the following combination of elements:
a vapor-permeable upper which is associated with a vapor-permeable or perforated lining;
a tread sole made of perforated elastomer;
a mid-sole which comprises at least one membrane made of waterproof and vapor-permeable material which is associated with a lower protective layer made of a material resistant to hydrolysis, water-repellent and vapor-permeable and/or perforated;
a vapor-permeable or perforated insole;
a vapor-permeable or perforated filler layer arranged between said insole and said membrane,
said shoe being characterized in that said membrane is arranged in a preassembled insert, to which it is sealed at its edge regions, said insert being suitable to provide support for said membrane both during assembly and during use.
This invention also concerns a vapor-permeable, water-repellant or waterproof, preassembled insert capable of being precisely and easily included into a sole assembly during manufacture of a shoe. The insert comprises a vapor-permeable, waterproof membrane having upper and lower faces and an edge face, a vapor-permeable or perforate protective layer adjacent to and in contact with said lower face, and a waterproof supporting grid adjacent to and in contact with said membrane, said supporting grid being bonded to said membrane at least at the periphery of said membrane. The bonding may be accomplished at the perimeter of said upper face of said membrane, at the perimeter of said edge face or at the perimeter of both said upper face and said edge face.